<script>
//设计一个a，使得a===1 && a===2 && a===3 === true

//1、利用数组或对象。只能实现==时为true
Array.prototype.toString = function (){
    return this[0]++
}
let aa = [1]
console.log(aa==1 && aa==2 && aa==3)

//2、能实现===时也为true
let value = 1
Object.defineProperty(window, 'aaa', {
    get(){
        return value++
    }
})
console.log(aaa===1 && aaa===2 && aaa===3)

</script>